Alkylation of aromatics



Patented Nov. 12, 1946 ALKYLATION OF AROMATICS Carl 31mm, Riverside, andVladimir N. Ipatieff,

Chicago, 111., assignors to Universal Oil Products Company, Chicago,111., a-corporation of Delaware No Drawing. Application December 20,1944, Serial No. 569,098

1 14 Claims.

The present invention relates to the interaction of alkylatable aromatichydrocarbons with olefinic hydrocarbons in the presence of a novelalkylation catalyst. It is more particularly concemed with theproduction of alkylatable hydrocarbons which can be used asintermediates in the manufacture of synthetic rubber or can beincorporated into gasolines to form premium fuels. This application is acontinuation-in-part of our earlier application Serial No. 470,223,filed December 26, 1942, now Patent No. 2,366,736, grantedJanuary 6,1945. i

The alkylation of aromatics, particularly benzene with ethylene, hasbecome very important at the present time. The primary product of thereaction, ethyl benzene, upon dehydrogenation yields substantialquantities of styrene which is now extensively employed in themanufacture of synthetic rubber. Ethyl benzene, isopropyl benzene andsimilar compounds have been found to have excellent antiknock propertiesand are valuable as addition agents to gasolines.

In one embodiment the present invention comprises a process for thealkylation of an alkylatable aromatic compound with an olefin,particularly ethylene, in the presence of boron trifiuoride and an acidfluoride.

The two components which, when combined, form our novel alkylationcatalyst when used individually do not catalyze the interaction of anaromatic with an olefin to any great extent. We have found that uponcombination these materials produce a very effective catalyst as isborne out by the experimental data presented hereinafter in thisspecification. These catalysts possess qualities which make their use oncommercial operation particularly attractive. Perhaps the most importantcharacteristic of these catalysts is their ability to catalyze theinteraction of benzene with ethylene, as well as with higher boilingolefins. With most of the prior art al- ,kylation' catalysts, forexample, sulfuric acid, it

has been found that while these catalysts are efiective in causing theinteraction of benzene with propylene, butylene, etc., they do notpossess the ability to efiect interaction of benzene and ethylene.

Benzene and other aromatics may be readily obtained by the distillationof coal tar products or may be found in substantial quantities instraight-run gasolines from various crude oils, particularly the coastalcrude oils. These aromatics may also be produced by the catalyticdehydrocyclization of normal parafiins having at least 6 carbon atoms tothe molecule or by the 2 catalytic dehydrogenation of naphthenic orcyclic olefins having a ring structure comprising at least 6 carbonatoms. The olefins may be obtained in large quantities in the gaseousproducts from cracking and other hydrocarbon conversion operations or bythe dehydrogenation of such compounds as ethyl alcohol. Although thecatalysts of the present invention are particularly applicable whenethylene is employed as the alkyl ating agent, our invention is broaderin scope and the catalyst may be used generally for reacting aromatichydrocarbons or aromatic compounds such as halogenated aromatics,phenols, etc., with either normally gaseous or normally liquid olefinichydrocarbons, particularly olefins containing from 2 to about 12 carbonatoms per molecule or compounds capable of forming olefins under theparticular set of conditions selected for the operation. In certaininstances, polymers of the lower boiling olefins may be employed, al-

though not necessarily under the same operating conditions. For example,when olefinic polymers are reacted with the aromatic, it is generallydesirable to employ a somewhat higher ratio of aromatic to olefin in thehydrocarbon charging stock than would ordinarily be used when monomericolefinic reactants are employed.

As previously stated, boron trifluoride or the acid fluorides alone arenot alkylating catalysts. However, when employing the two together, anactive catalyst is obtained. While the catalyst has been found topossess some activity regardless of the proportions of boron trifluorideand acid fluoride, the best results are obtained when a definite molalexcess of BF: over the acid fluoride is maintained.

The alkylation reaction in the presence of the boron trifluoride alkalimetal acid fluoride catalyst may be carried out at a temperature fromabout -l0 C. to about 400 C., although a more preferable operating rangeis from about 10 C. to about C. It is highly desirable that the reactionbe carried out under sufiicient pressure to maintain a substantialportion of the reactant in the liquid phase, for example, from about 10to about 200 atmospheres, depending upon the amount of boron trifluoridepresent, the temperature of the reaction and other factors. In order tominimize polymerization of the olefinic reactants, a hydrocarbon feed tothe alkylation zone should contain a substantial excess of aromatichydrocarbons over the olefinic hydrocarbons, for example, a molal ratioof aromatics to olefins of about 2:1 to about 20:1 or higher.

If desired the olefinic reactants-may be introduced at spaced 3 I pointsthroughout the alkylation zone in order to maintain the desired higharomatic to olefin ratio. In the case of the preferred operation whereinpotassium or sodium acid fluoride is maintained as a fixed bed, theeflluent material from the alkylation zone is introduced into aseparation step wherein hydrocarbon reaction products are sepaamounts ofethane, propane, or normal butane are introduced with the freshhydrocarbon feed it will be desirable to remove these constituentsduring the fractionation operation. In general it is not intended tolimit the broad scope of the present invention to any particular methodof contacting the catalyst and the reactants.

The following examples are introduced in order to illustrate the natureof the present invention as it is applied to the alkylation of benzenewith ethylene. a

In these examples a rotating autoclave of about 850 cc. capacity wasemployed as a reaction zone. The autoclave was rotated at the specifiedtemperature for about 4 to 6 hours, then cooled to room temperature andthe pressure released through bubblers containing caustic solution. Thenon-condensible gas was measured in a gas meter and subsequentlyanalyzed. The autoclave was then opened and the liquid reaction productremoved therefrom, washed, dried and distilled.

The following table presents the operating conditions employed and theresults obtained when alkylating benzene and ethylene in the presence ofboron trifluoride.

Experiments 1 and 2 indicate that the individual materials do notpossess any activity as alkylation catalysts, but it is only when usedin conjunction with one another that. an active alkylating catalyst isobtained.

Experiment number Conditions:

emperature, C 25 25 300 120 Hrs rotated at tem u- Charge, g.: p 6 6 4 6lF F1 0 15 40 15 B a 18 43 1345332155. 160 160 160 160 Recovery, g.: n24 24 38 30 Eth ene 24 0 6 3 Benzene 160 Ethylbenzene 52 78 52 Dethylbenzenes 16 26 15 Higher ethylated benzene 4 14 9 We claim as ourinvention: 1. A process for the synthesis of organic compounds whichcomprises reacting an allgvlatable aromatic compound with an alkylatingagent under alkylating conditions in the presence of boron trifluorideand an acid fluoride.

2. A process for the synthesis of hydrocarbons which comprises reactingan alkylatable aromatic hydrocarbon with an olefinic hydrocarbon underalkylating conditions in the presence of boron trifluoride and an acidfluoride.

3. A process for the alkylation of aromatic hydrocarbons with olefinichydrocarbons which comprises contacting aromatics and olefins at atemperature of from about 10 C. to about 400 C. in the presence of borontrifiuoride and an acid fluoride.

4. A process of claim -1 further characterized in that said acidfluoride comprises an acid fluoride of an alkali metal.

5. A process for the synthesis of organic compounds which comprisesreacting an aromatic compound with an alkylating agent under alkylatingconditions in the presence of boron trifluoride and an acid fluoride ofpotassium.

6. A process for the synthesis of hydrocarbons which comprises reactingan aromatic hydrocarbon with an olefinic hydrocarbon under alkylatpoundswhichcomprises reacting an. aromatic compound with an alkylating agentunder. alkylating conditions in the presence of boron trifluoride and anacid fluoride of sodium.

8. A process for the synthesis of hydrocarbons which comprises reactingan aromatic hydrocar bon with an oleflnic hydrocarbon under alkylatingconditions in the presence of boron trifluoride and an acid fluoride ofsodium.

9. A process for the synthesis of hydrocarbons which comprisesalkylating benzene with ethylene in the presence of boron trifluorideand an alkali metal acid fluoride.

10. A process for the synthesis of hydrocarbons which comprisesalkylating benzene with propylene in the presence of boron trifluorideand an alkali metal acid fluoride.

11. A process for the synthesis of hydrocarbons which comprisesaikylating benzene with ethylene in the presence of boron trifluorideand an" alkali metal acid fluoride.

12; A process for the synthesis of hydrocarbons whlch'comprises passingaromatic hydrocarbons, oleflnic hydrocarbons and boron trifluoridethrough an alkylating zone containing therein a fixed bed Of solidcontact material comprising an alkali metal acid fluoride, separatingboron trifluoride from the hydrocarbon reaction products, recycling saidboron trifluoride to the alkylating zone and fractionating saidhydrocarbon reaction products to recover desired alkylation products.

13. The process of claim 12 wherein said solid contact material consistsessentially of potassium acid fluoride as its active ingredient.

14. A process of claim 12 wherein said solid contact material consistsessentially of sodium acid fluoride as its active ingredient.

CARL B. LINN.

VLADIMIR N. IPA'I'IEFF.

